If you use the Morgan for touring a "sports" exhaust may start to get annoying on a long trip. If you finish up with ringing ears at the end of a trip it is too loud and you risk hearing damage in the long term. We have a sports exhaust on our car but it has not been too loud for us but the tone and volume has been improved (lower) since I fitted a better quality and larger cat.
Wind noise with the hood up is not bad but we did have a problem with the hood flapping at Autostrada speeds. I managed to fix that. See
http://www.talkmorgan.com/ubbthreads.php/topics/167781/stop-the-flapThe other thing that I have done is fit the new style windscreen pillar rubbers. By fitting them over the top of the existing flat rubbers. This pushes the side screens out a little but the alignment from the sidecreens, the new rubbers and the windscreen pillars is much better. I think it gives better, and quieter, air flow. The increased pressure of the side screens against the rubbers may require some adjustment of the side screen brackets but it may also stop the side screen flutter that occurs on some cars.
If you decide to remove the existing pillar rubbers be very carefull because the coating on the pillars can be pulled off

I don't have an answer to this other than the careful use of a mild solvent (lighter fluid, turps).
It probably does not make much difference to wind noise but I have small neoprene pads on the top of the windscreen pillars to stop the occasional drip of rainwater that used to enter there.
If ever you think to come up to Lake Como do get in touch.